Manage your subscription

Eye receptor transplant promises therapy for blindness

By Andy Coghlan

FOR the first time, the light-sensing cells found in the retina have been grown from scratch in the lab and transplanted into the eyes of blind mice. The transplanted cells matured and connected with nerves that transmit visual signals to the brain.

If the procedure can be repeated with human stem cells, researchers believe they could cure most forms of blindness that result from the degeneration of photoreceptor cells.

Robin Ali of University College London and his colleagues made the photoreceptors using a relatively new procedure that allows embryonic stem cells to self-organise into retina-like structures within a three-dimensional blob of jelly.

Crucially, they also identified the optimal stage in the cells’ development to transplant them into the eyes of mice&colon; 24 days. At this point the photoreceptor cells are still relatively immature, but when implanted into the eye they find their own way to where they are needed and then mature fully (Nature Biotechnology, doi.org/m9c).

Advertisement

If the cells passed the 24-day mark outside of the eye they become photoreceptor structures called outer segments, which are not able to find their way when transplanted, says Ali.

“We now have a route map for doing this with human embryonic stem cells,” he says. The team has already grown the precursors to human retinal photoreceptor cells. “The challenge is to get [the procedure] efficient enough for transplants,” he says.

In the meantime, Ali’s team wants to carry out more transplants in mice and show that these mean they can see. They say that although the transplanted cells developed and connected up to nerve cells successfully in the first attempt, not enough cells were implanted to restore the mouse’s vision. “It’s a numbers game,” says Ali.

“Until recently, photoreceptor loss was thought to be irreversible, but there’s now enough evidence to think we might be able to reverse blindness in the future,” says Robert Lanza, medical director of Advanced Cell Technology, a company that specialises in stem cell trials based in Marlborough, Massachusetts. “But it needs to be repeated using human cells, and there are lots of technical issues that need to be addressed, such as scaling up the three-dimensional culture system.”

There’s now enough evidence to think we might be able to reverse blindness in the future

This article appeared in print under the headline “Blind mice receive brand new light-sensing cells”